Download Cellular Respiration

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Cellular Respiration
Filename: Respire.ppt
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Lecture Outline
• Using Chemical energy to drive metabolism
• Production of ATP
• Cellular respiration
– Clycolysis
– Krebs cycle
– Electron transport
– Chemiosmosis
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Lecture Overview
• All organisms drive their metabolism with
ATP generated from
• Rearrangement of chemical bonds
• Energetic electrons from proton pumps
• Electrons from photosynthesis
• Electrons from oxidation of sugars and fats
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Background Terms & Concepts
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Glucose
Chemiosmosis
Oxidation- reduction
ATP
Exergonic vs endergonic reactions
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Concepts from OAC
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Synthesis of ATP
Glycolysis: Krebs cycle
anaerobic vs aerobic glucose catabolism
Energy from fats & proteins
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Energy Flow & Recyling
Energy Rich
Energy Poor
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Cellular Respiration
• Release of energy stored in organic
compounds
– Carbohydrate
– Fats
– Proteins (net energy loss)
• Oxygen is consumed as a reactant
• Carbon dioxide and water are byproducts
• Energy is used indirectly
– trapped as ATP
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Pathways in Cellular Respiration
• Glycolysis
• Krebs cycle
• Electron transport chain
Cellular Respiration
Cumulative function of three
metabolic pathways and
chemiosmosis
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Catabolism of various foods
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A room of your own...
Overview of Cellular Respiration
ATP
ATP
ATP
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Glycolysis occurs
whether or not oxygen is
present
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Glycolysis
• OCCURS in the CYTOPLASM
• Glucose (6 carbon sugar) >>>
2 pyruvate (3 carbon sugar)
• Energy investment phase
• Energy yielding phase
• Net yield of energy
No Carbon dioxide is released
during glycolysis
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Electron
Transport
System
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Glycolysis
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Glycolysis: Energy Investment
• Glucose + ATP-> glucose-6-P + ADP
– hexokinase
• Glucose-6-P -> Fructose-6-P
– phosphoglucoisomerase
• Fructose-6-P + ATP -> Fructose 1,6,
diphosphate + ADP
– phosophofructokinase
• Fructose 1,6,diphosphate -> glyceraldehyde
phosphate + dihydroxyacetone phosphate
– aldolase
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Energy Investment Phase
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ATP Investment
More ATP investment
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Isomerization
• glyceraldehyde phosphate &
dihydroxyacetone phosphate are isomers
– Isomerase interconverts
– glyceraldehyde phosphate removed next as
next step
• THUS Equilibrium between the two sugars
is in direction of glyceraldehyde phosphate
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Glycolysis: Energy Yield Phase
• Glyceraldehyde-P + 2NAD+ +2Pi ->
1,3 glycerophosphate + 2 NADH + 2 H+
• !,3 glycerophosphate + 2ADP ->
3 phosphoglycerate + 2 ATP
• Relocate phosphate group
• Remove water to create phosphoenolpyruvate
• Remove phosphate from PEP
• PEP + 2ADP -> pyruvate + 2ATP
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Substrate level Phosphorylation
The first payoff (substrate-level phosphorylation)
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More Energy Payoff
More dividends (substrate-level phosphorylation)
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Glycolysis: Net Energy Yield
• Glucose >>> 2 pyruvate
• 2 ADP >>> 2 ATP
• 2 NAD+ >>> 2NADH
NADH>>> electron transport chain
if oxygen is present
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Alternate Glycolytic Pathway
• Glycolysis
• Embden-Meyerhof
• Glucose>> glucose-6
phosphate
• Fructose-6 phosphate
• Fructose 1,6 diphosphate
• ISOMERS
– dihydroxyacetone
phosphate
– Glyceraldehyde 3 P
• Alternate
• Enter-Doudoroff
• Glucose>> glucose-6
phosphate
• 6 phosphogluconic acid
• Keto deoxy 6
phoshogluconic acid
• pyruvic acid +
Glyceraldehyde 3 P
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Pyruvate
Fermentation
Oxidative
phosphorylation
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Role of Pyruvate
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Formation of Acetyl CoA
• Pyruvate translocated from cytoplasm to
mitochrondial matrix
• Pyruvate + NAD+ -> Acetate + NADH +
CO2
• Acetyl group attached to Coenzyme A
Acetyl CoA links glycolysis to
the Krebs cycle
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Formation of Acetyl CoA
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Krebs cycle
• oxidation of pyruvate generated by glycolysis
– glucose->2 pyruvate
• Generates 1 molecule of ATP/ pyruvate
– substrate level phosphorylation
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Generates 4 molecules of NADH / pyruvate
Generates 1 molecule of FADH2/ pyruvate
Generate 3 molecules of carbon dioxide
OCCURS in MITOCHONDRIAL MATRIX
occurs in prokaryotic cytoplasm
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Krebs cycle
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Summary of Krebs Cycle
IN
Out
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Out
Out
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IN
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Krebs Cycle Balance Sheet
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Input
Water
ADP
NAD+
FAD+
Acetyl CoA
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Output
Carbon Dioxide
ATP
NADH
FADH
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